Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
Yes, both boards were in standby (power connected, but not turned on).
A little bit amusing maybe.. there is no element on the topside at C910. So.. I'm not sure what to think about that....
aecune
Member
Last Activity: 11-01-2019, 10:58 PM
Joined: 08-25-2019
Location: Boise, ID
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
I replaced the power board and now my TV is back online. Thanks for the effort, all.
I'm going to try to find the root cause by comparing the two. I would still love any assistance if anyone is interested in getting to the root cause here, as the original board is still broken.
Edit: Found that C910 and C908 have different values [I]while in circuit[/I], which seems to indicate something nearby is different. This is shown in picture. Capacitors in red have 73uF capacitance in good board, 140uF...Last edited by aecune; 10-26-2019, 02:11 PM.Leave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
Good question. It's 0.1 ohm. So the measured value of R804 is within a rounding error.
Any other ideas? Did you see anything strange with my voltage readings in the picture of my last post?...Last edited by aecune; 10-20-2019, 05:29 PM.Leave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
Did more testing of the voltages, as well as checking the resistors again. Also checked continuity.
1) Found nothing continuous with Pin1 + 3 of IC901. 3 is GND--maybe no issue. 1 is "S", which is source terminal of internal power MOSFET. PDF recommends connecting with a sense resistor to GND--maybe also not an issue.
edit: Pin 1 and 3 are continuous with an elements closer to the main cap, so soldering is not an issue.
2) Many of the resistors appear to have no power across...Last edited by aecune; 10-19-2019, 03:47 PM.Leave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
I replaced the zener, but still no dice. Going to recheck all my soldering tomorrow as best as I can, though I'm not 100% sure of which items connect to which, without a wiring diagram for this board. I'll also check voltages on various nodes to see if there are changes in the voltage.Last edited by aecune; 10-19-2019, 02:30 AM.Leave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
Thanks a lot for the help so far, R_J and budm. I have one question regarding identifying ZD909; it is marked NZ 4V7[B]D[/B] or NZ 4V7[B]0[/B]--it's hard to distinguish the last letter. Regardless, I cannot find anything online with this information, except, incidentally, another badcaps thread thread with you gentleman in it :-)
[url]https://www.badcaps.net/forum/showthread.php?p=851050[/url]
Within that thread, budm had the following exchange:
OP: "Only found 2 bad diodes....Leave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
OK I see it now. I was looking for the element from the top-side of the board. Values are:
R908A - 1.5Ω
R908B - 1.5Ω
R908C - 1.5ΩLeave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
1) I pulled ZD909 out half-way, and I was getting 0.018V in both orientations. This seems to confirm that it's kaput.
2) I checked resistance across what I think is pin 1 and 4 of T901 and got 0.5Ω. Picture is attached of this resistance reading.
3) I'm not sure where R908A-C are. Did you take those values from my screenshot? I was not able to find any resistors of this number, nor any that had an A-C series....Leave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
Thanks for the replies. I wasn't available during the week so I couldn't reply.
Using an un-powered circuit, I investigated the diodes surrounding the IC and everything had a forward voltage of 0.6V, except for ZD909 (to left of IC). It had 2.1 ohm resistance, and 0V reading (using diode setting on DMM), in either direction. This seems to indicate that it's toast, no?Leave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
Measuring the voltage between the negative leg of main filter cap and each pin on the IC, I got the following results (in DC):
Pin1 (top left): 0
Pin2: 0
Pin3: 0
Pin4: 0
Pin5 (VCC): 10-20V (consistently varies wildly, it is unstable)
Pin7: 166V
Pin8: 166V
Measuring D902B bottom-side results in same fluctuating voltage as Pin5, so I assume this is upstream thing? Not sure if this is even something to be concerned about?
(I began measuring VAC...Last edited by aecune; 09-30-2019, 12:08 AM.Leave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
I understood hot-ground to refer to the "negative" of the 120V from the wall. Here is a picture of my circuit board.
I think what I did actually only indicates that I have no power across the components. The voltage is the same as the line voltage. Where is the main filter cap? Is it the large capacitor in brown at the bottom left of the board?...Last edited by aecune; 09-29-2019, 11:05 PM.Leave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
OK, using the hot ground, I am getting 60-61VAC on all IC terminals. Therefore, it appears that I have standby voltage.
Edit: In case it's significant, I measured many of the resistors on the secondary circuit on the power board, and received 66VAC.Last edited by aecune; 09-29-2019, 10:17 PM.Leave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
I finally got the IC from China and was able to replace it and the capacitors. Unfortunately, this didn't solve the problem. The TV still displays no picture, and the LED does not light-up.
I measured the voltage from the board's ground to VCC of the IC and got 9VAC. Double checked the fuse (was never in doubt) and I have continuity across it.
Checked from GND of IC to VCC and had fluctuating voltage. This seems like it could be significant, but I'm not positive.
Anything else...Last edited by aecune; 09-29-2019, 02:50 PM.Leave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
Right, you are correct SLK--a cap shouldn't have continuity! I wasn't thinking. I don't typically measure caps so I'm not sure how to explain that behavior other than what you suggested.
R_J, mind if I pick your brain to understand this better? What clue'd you into those caps? And what is standby IC?
I'll go ahead and replace them and report back. Thanks for the help.Leave a comment:
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Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
Hi R_J. Not sure where 903 came in. You are correct, it is IC 901! [B]Edited original post to reflect this.[/B]
Why do you recommend replacement of these two caps?
For what it's worth, I'm getting poor continuity on C907--or at least, it's just for a fraction of a second, and then no more. IC904B has consistent continuity. Is this significant?
[url]https://ibb.co/h2gHZVQ[/url]Re: Vizio E550i-B2 no power, no sound, no LED -- blown IC found
...Leave a comment:
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Vizio E550i-B2 no power, no sound, no LED -- blown IC found
Power board model: 056.04167.1071
My TV had an issue six months where it had no picture, no sound, yet a picture could be seen using a flashlight. I was able to resolve this common problem simply by re-soldering (apparently its a problem documented on this forum too: [url]https://www.badcaps.net/forum/showthread.php?p=872360&highlight=ViZio+E550I#post872360[/url])
My current problem is different, as the power LED won't turn on, so I opened up the TV and examined the components.
I found that IC901 has exploded. Another badcaps user reported the same issue....Last edited by aecune; 08-25-2019, 02:06 PM. -
Re: New Members - please post your introductions here
Hello, I am Jonathan from Boise, ID. I am repairing my Vizio TV and will likely try to use this forum as support in the future.Leave a comment:
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